Various types of electrical hand tool hammering apparatus are known. In one such structure--see, for example, Published European Patent Application No. 0054782, a hammer head element is returned to an initial or starting position by a spring. To absorb the shock of the returning hammer head, and thus prevent vibration and transfer of reactive forces to the operator's hand holding the apparatus, a rubber buffer is provided to accept the returning hammer head at the end of its returning movement. It has been found that the energy which is to be accepted by the rubber bumper or rubber buffer at times causes the rubber buffer to bounce, i.e. to propel the hammer element backwardly into its working or operating direction. A feeding blade operated by the hammer element, for example a blade which feeds a staple or a nail from a supply magazine can then sever a nail or staple from the supply stack by the returning bouncing blade and can transport the thus severed fastening element, into the guide or injection duct towards the nailing or stapling position without, however, ejecting the nail or staple. The hammer head is then returned to its initial position by the spring. Upon a subsequent operation of the hammering gun, a further fastening element is severed from a magazine stack which will interfere with the already present previously introduced fastening element, resulting in faulty operation and, under particularly poor operating conditions, jamming of the guideway.
It has been proposed--see the referenced European Patent Application No. 0054782--to provide a system which prevents projection of the hammer head after an operating stroke, unless specifically controlled to do so. The system there proposed is comparatively complex and requires additional space. Further, it is subject to rapid wear, requiring frequent exchange of the buffer or bumper accepting element. To permit such exchange of this element, which, normally, is securely retained within the housing of the tool, requires further structural changes to standard housings, additionally increasing the complexity of the structure, and requiring careful maintenance thereof.